Using the stack class


>>> s = Stack()
>>> s.push("one")
>>> s.push("two")
>>> s.stack
['one', 'two']
>>> s.pop()
'two'
>>> s.pop()
'one'
>>> s.pop()
Traceback (innermost last):
  File "<pyshell#34>", line 1, in ?
    s.pop()
  File "<pyshell#23>", line 9, in pop
    return self.stack.pop()
IndexError: pop from empty list